Distribution, frequency of occurrence and population density of root knot nematode in Hamelmalo – Eritrea

Abstract

A survey was conducted during January to May 2011, to assess the occurrence and population density of root-knot nematode on different crops in 13 different localities of Hamelmalo subzone (Eritrea). A total 449 samples were collected from the study area and nematodes in their rhizosphere soil and root extracted by Cobb’s decanting and sieving technique, Baermann funnel technique and root maceration methods. Out of the 449 collected samples, 344 samples were found to be infested with root knot nematode as soil population was visible. Awatle (97.8%), Shewwa (90%) and Engdaw (88.2%) are the provinces of the Hamelmalo that had very high population of root knot nematode. The least infection was reported from the Stur (52.3%) province. At individual crop level, the highest frequency of occurrence was reported from tomato (86.5%) and least was from rocket (50%) crop. Root knot nematode population in 100 cc soil (density) was reported as maximum (73.5%) for the chilli crop and minimum (12.24%) for the rocket vegetable. Measurement of disease incidence was based on the gall index and egg mass index, and this varied from 2 to 5 on 5 point scale. Highest disease incidence (5 GI and EMI) was reported from tomato, okra and potato crops, followed by the spinach, chilli and molukhyia crop, while the least disease incidence (2 GI and EMI) was reported from the rocket crop. Key words: Root knot nematode, vegetable crops, frequency, density, disease incidence, Hamelmalo.